围护结构热工性能现场检测技术分析与探讨

简要介绍了围护结构热工性能现场热流计法的检测原理,并结合现场检测经验与相关标准提出对热流计传感器的校对和一些使用要点和技巧以及热流计法在建筑节能现场检测中的应用。     

Estimation of thermophysical properties using natural signal analysis with heat and moisture transfer model

Conduction heat transfer through opaque envelope components characterizes the thermal performance of buildings and its consequences in terms of energy consumption and thermal comfort. A building envelope can be thermally described by two parameters: thermal conductivity (λ) and heat capacity (ρ·c). Estimating these thermal properties in situ allows the characterization of real building elements considering different aspects, such as thermal behavior under specific weather conditions, quality variability in materials, local construction technologies and material deterioration. This paper presents a method to estimate the thermal conductivity and volumetric heat capacity of a homogeneous element using a non-destructive test considering natural oscillations. Surface temperature and heat flow are measured in a concrete sample (with known thermal properties) and the data is treated with a signal processing technique. Estimation is carried out with a heat and moisture transfer model. Measurements were performed on six separate days under different sky conditions within a period of one month, to determine the importance of solar radiation as a heat source. Results gave acceptable estimates (average inaccuracy of 10-14%) of both thermophysical properties.     

Performance analysis of the building envelope: A case study of the Main Hall,Shinawatra University

The envelope of the Main Hall, Shinawatra University has been designed to provide protection from energy gain. According to initial estimates, the Main Hall could achieve an overall thermal transfer value (OTTV) of 10.16 W/m², which is four times lower than those recommended by the Thai national standard. This study aims to evaluate the actual energy performance of the Main Hall building envelope using field measurements and simulations. The air temperature, surface temperature, and relative humidity were measured at frequent intervals, both indoors and outdoors. Hourly average meteorological data for insolations were utilized in order to calculate the solar gain by light transmission. Based on the empirical data, the energy fluxes through the envelope on eight different orientations were simulated and the average value was found within 7% of the estimated OTTV. Using the same empirical data for the outdoor condition, simulations of other common types of building envelope in Thailand were carried out for comparison. The results of the analysis show that the Main Hall's lightweight and highly insulated building envelope outperforms other commonly used heavyweight envelopes in preventing building energy gain in the hot-humid climate of Thailand. Although the use of the lightweight and highly insulated envelope helps reduce the operating and investment costs of the air conditioning system as well as the cost of building structure, it also increases the investment cost of the envelope substantially. However, the life cycle cost analysis (LCCA) reveals that the life cycle cost (LCC) of the Main Hall envelope is the most economical, and the increased investment cost of the Main Hall envelope requires a discounted payback period of only 3–5 years, depending on the envelope types used in the comparison. Furthermore, it should be noted that greater savings and a more favorable pay back period could be obtained if this highly energy efficient envelope is applied to other typical buildings, especially high-rise structures in urban areas.     

Evaluation of energy efficient design strategies for different climatic zones: Comparison of thermal performance of buildings in temperate-humid and hot-dry climate

Since the Kyoto protocol signed in December 1997 the majority of governments around the world have committed themselves to reducing the emission of the greenhouse gases. Thus, efficient use of energy and sustainability has become a key issue for the most energy policies. Sustainability and energy saving terms take place in building construction industry too since buildings are one of the most significant energy consumers. It is known that heating energy demand of a building has a great rate in building total energy consumption. In addition to that, the most of the heating energy has been lost from building envelope. TS 825, Heating Energy Conservation Standard for Buildings in Turkey, aims the reducing of heat loss in buildings through the envelope. But within buildings, one of the fastest growing sources of new energy demand is cooling and especially in hot-humid and hot-dry climatic parts of Turkey cooling season is much longer than the heating season. Moreover in hot-dry climate heat storage capacity of the envelope becomes more important issue than heat insulation for energy efficiency of the building. Since the Turkish standard is considering only heating energy conservation by using degree-day concept, Istanbul and Mardin are considered in the same zone, however those are in temperate-humid and hot-dry climatic zones, respectively. In this study energy efficient design strategies for these climatic zones have been explained and thermal performance of two buildings, which are constructed according to the TS 825 in Mardin and Istanbul cities were evaluated to show the importance of thermal mass in hot-dry climates.     

节能建筑中应用保温砂浆的性能分析

随着环保和节能意识的增强,建筑节能正在成为世界建筑业的发展趋势,因此,建筑围护结构的绝热性能日益受到重视。保温砂浆通过改变其容重和厚度可以调节墙体围护结构的热阻,改善其热工性能,目前已成为我国重要的建筑节能技术措施之一,正在迅速发展并广泛应用工业与民用建筑中。基于保温砂浆的导热系数和蓄热系数及其大量的工程实践经验,分析了保温砂浆在我国节能建筑中应用的绝热机理和性能参数,进而综述了节能建筑对其性能的进一步要求,为拓宽保温砂浆在节能建筑中的应用范围奠定了基础。     

夏热冬冷地区绿色建筑的节能效益

针对目前常用绿色建筑节能技术及夏热冬冷气候特点,以案例形式分别对围护结构性能改善、能源综合利用等技术应用的效果进行分析,量化了绿色建筑节能技术的应用效益。研究结果表明:在目前常用的绿色建筑节能技术中,集中空调系统排风全热回收技术节能效益最大,达到35%节能率,过渡季节充分利用新风,会带来10%的节能率;合理设置可调节外遮阳和改变围护结构热工性能,可产生7%左右的节能率;采用光控措施控制照明系统,可形成12.3%的节能率;绿色建筑节能技术的选择及其应用效果受技术相互关联性影响较大,节能方案需要整体综合考量;节能技术的应用可使建筑在现行节能标准基础上再实现46.9%的节能率,达到建筑节能75%的要求。     

Life cycle cost implications of energy efficiency measures in new residential buildings

The importance of the built environment from an environmental impact and energy use perspective is well established. High thermal efficiency of the constructed building envelope is a key strategy in the design and construction of buildings which limit use of active space conditioning systems. Australia's current housing stock is thermally poor and national energy performance standards are relatively weak when benchmarked against international best practice. A lack of data has impeded the policy debate and a significant gap in analysis remains a lack of empirical research into the life-cycle cost implications of increased building thermal efficiency, particularly for residential buildings. This paper applies an integrated thermal modeling, life cycle costing approach to an extensive sample of dominant house designs to investigate life cycle costs in a cool temperate climate, Melbourne Victoria. Empirical analysis provides new insights into lifetime costs and environmental savings for volume housing design options and identifies sensitive factors. Results suggest that the most cost-effective building design is always more energy efficient than the current energy code requirements, for the full time-horizon considered. Findings have significant policy implications, particularly in view of present debates which frequently present higher energy efficiency standards as prohibitive from a costs perspective.     

ECOTECT能耗模拟下既有住宅建筑围护结构节能改造的热环境分析研究

目前,既有住宅建筑节能改造主要有围护结构改造和供热计量改造两方面。围护结构节能改造主要包括:外墙节能改造、外窗节能改造、屋面节能改造等技术措施的研究;建筑物围护结构节能改造除了能够降低建筑能耗之外,对建筑物室内热环境也有很大影响。采用ECOTECT能耗模拟软件,对西安市某住宅建筑围护结构不同节能改造方案的热环境进行模拟,深入分析不同节能改造方案的能源消耗、不舒适度、围护结构得热、温度分布和热舒适度情况,以热舒适为前提、节能为目的选择最优的节能改造方案。为既有住宅建筑节能改造方案优选提供依据。     

居住建筑围护结构的节能问题

从适宜居住的角度讲,我国绝大部分地区的居住建筑都要采取一定的技术措施来保证冬夏两季的室内热舒适环境。冬夏两季室内维持的温度与室外的温度有很大的差别,这个温差导致能量以热的形式流出或流入室内,采暖,空调设备消耗的能量主要就是用来补充这个能量损失的。在相同的室内外温差条件下,建筑围护结构保温隔热性能的好坏,直接影响到流出或流入室内的热量的多少。建筑围护结构保温隔热性能好,流出或流入室内的热量就少,采暖,空调设备消耗的能量也就少;反之,建筑围护结构保温隔热性能差,流现或流入室内的热量就多,采暖,空调设备消耗的能量也就多。我国现行的居住建筑节能设计标准对建筑围护结构保温隔热性能提出了明确的要求,按照节能设计标准的要求去设计,新建的居住建筑就能比具有传统围护结构的同类建筑节约25％－35％的采暖,空调能耗,而且节能的潜力还十分巨大。     

New concepts and approach for developing energy efficient buildings: Ideal specific heat for building internal thermal mass

The shortcomings or limitations of the traditional approach to developing energy efficient buildings are that they can not determine: (1) the ideal thermophysical properties of building envelope material, where “ideal” means that such material can use ambient air temperature variation and/or solar radiation efficiently to keep the indoor air temperature in the thermal comfort range with no additional space heating or cooling; (2) the best natural ventilation strategy; (3) the minimal additional energy consumption for space heating in winter or air-conditioning in summer. To overcome these problems, some new concepts for developing energy efficient buildings are put forward in this paper. They are the ideal thermophysical properties of the building envelope material, the ideal natural ventilation rate, and a minimal additional space heating or cooling energy consumption. A new approach for determining these properties is also developed. In contrast to the traditional approach (the thermophysical properties of building envelope material are known and constant so that the relating equations describing the indoor air temperature tend to be linear differential equations), the new approach solves the inverse problem (thermophysical properties, etc. of a buildings are unknown), whose solution can be a function instead of a value. As a first step, the ideal specific heat of the building envelope material for internal thermal mass is analyzed for buildings located in various cities in different climatic regions of China, such as Beijing, Shanghai, Harbin, Urumchi, Lhasa, Kunming and Guangzhou. We found that the ideal specific heat is composed of a basic value and an excessive one which is of δ function for the cases studied. Some limitations that would need further study are introduced in the end of the paper.     

Assessment of thermal behaviour of thermo-active diaphragm walls based on monitoring data

Thermo-active diaphragm walls have proved their effectiveness in the thermal conditioning of buildings and infrastructures. However, some aspects still need to be investigated in order to tailor methods and tools for an accurate prediction of their energy and structural performance. In this perspective, some issues are addressed that concern the definition of models for the numerical analysis, in particular issues about the modelling of geometry and thermal boundary conditions. Taking advantage of a monitoring programme on a real full-scale structure, this research focuses on the assessment of heat transfer process and thermal response of diaphragm wall and soil mass on the basis of field data. Understanding of the heat transfer process contributes to the definition of the time-dependent thermal boundary conditions at the excavation side. From the analysis of thermal gradients in the wall, the condition at the excavation side is recognised as a major factor that influences the heat transfer process, governing the direction of the heat flux in different seasons of operation of the geothermal system.     

建筑围护结构热工性能现场检测技术探讨

对建筑围护结构热工性能现场检测技术进行了总结,指出为了系统全面地评价围护结构节能效果,应对现场测试装置进行改进,并检测更多的热工参数,为建筑物的运行能耗分析提供依据。     

编制《内蒙古公共建筑节能设计标准》的几个相关问题

在全国大力推行节能减排的形势下,《内蒙古公共建筑节能设计标准》(DBJ 03-27-2007)顺应建筑节能发展需求,经多方论证现已完善成稿并于2007年11月发布。在编制过程中,笔者主要负责建筑与建筑热工设计部分的编制工作,包括内蒙古公共建筑节能设计气候分区、外围护结构的构造设计、建筑外围护结构热工性能的权衡判断与计算以及外墙平均传热系数的简化计算,对这4个主要问题做了较为切合本地区实际情况的具体规定。     

南方建筑非透明围护结构热工与节能设计

如何兼顾冬夏两季建筑供暖空调负荷和能耗,保证室内热环境质量,确定最适宜的热工特性,是长期困扰中国南方建筑围护结构热工与节能设计的难点。通过对夏热冬冷和夏热冬暖地区建筑在采暖、空调与自然通风条件下动态热过程的分析,研究了这一地区围护结构热特性与能耗的制约关系,以及对室内热环境与建筑热稳定性的作用机理。在兼顾冬季保温与夏季隔热的情况下,将建筑全年能耗作为控制目标,从室内热环境质量、节能效果、围护结构的安全性、可靠性、经济性和实用性等角度评价目前所采用的围护结构节能技术存在的问题,提出一种适宜南方气候的建筑围护结构热特性指标及构造形式。     

贵州民用建筑围护结构节能技术适应性分析

围护结构的热工性能是影响民用建筑能耗的最重要因素之一,如何正确地应用围护结构节能技术尤为重要。地方标准将贵州划分为四个气候区域,即温和地区、夏热冬暖地区、夏热冬冷地区、夏凉冬冷地区[1]。为了使围护结构节能技术的应用更加有效,根据贵州省四个气候分区特点,对民用建筑围护结构典型节能技术进行研究分析,结合相关建筑节能标准的要求和贵州省经济、环境特点,提出适合贵州不同气候区域民用建筑的墙体、外窗、屋面、遮阳节能技术。     

Cool roofs impact on building thermal response: A French case study

The refurbishment of building roofs with cool selective coatings is already defined by some standards. Impacts on urban heat island (UHI) and thermal performance of buildings are well identified. In France, most of the developments on building thermal performances are focused on the building envelope insulation, especially for the winter energy performance, and the cool roof technique as a part of the solution for summer conditions is not well established. This passive technique for cooling the cities and indoor environments has a performance depending on the climatic location and constructions morphology. In this paper, we focus on a case study in Poitiers (France): a cool roof for a low-rise building (public housing), without any cooling active system.The performance of the cool coating is detailed through experimental results, completed by a dynamic simulation work on the studied building. In a first part, the case study is presented; the surface temperatures and the climatic conditions were monitored indoor and outdoor. Then, a dynamic simulation for the summer period is compared to the experimental results. This audit study of the actual case study permits the analysis extension of thermal condition in order to compare the performance of the envelope toward the cool roof. This first case study analysis will help understanding the cool roof potential and limitations in a French context. These results will have to be projected for various construction typologies in order to help its development in the different climatic regions. It will be also a part of different European climate first comparison through the work of the EU cool roof project.     

Application of latent heat thermal energy storage in buildings: State-of-the-art and outlook

Latent heat thermal energy storage (LHTES) is becoming more and more attractive for space heating and cooling of buildings. The application of LHTES in buildings has the following advantages: (1) the ability to narrow the gap between the peak and off-peak loads of electricity demand; (2) the ability to save operative fees by shifting the electrical consumption from peak periods to off-peak periods since the cost of electricity at night is 1/3–1/5 of that during the day; (3) the ability to utilize solar energy continuously, storing solar energy during the day, and releasing it at night, particularly for space heating in winter by reducing diurnal temperature fluctuation thus improving the degree of thermal comfort; (4) the ability to store the natural cooling by ventilation at night in summer and to release it to decrease the room temperature during the day, thus reducing the cooling load of air conditioning. This paper investigates previous work on thermal energy storage by incorporating phase change materials (PCMs) in the building envelope. The basic principle, candidate PCMs and their thermophysical properties, incorporation methods, thermal analyses of the use of PCMs in walls, floor, ceiling and window etc. and heat transfer enhancement are discussed. We show that with suitable PCMs and a suitable incorporation method with building material, LHTES can be economically efficient for heating and cooling buildings. However, several problems need to be tackled before LHTES can reliably and practically be applied. We conclude with some suggestions for future work.     

Impact of adaptive comfort criteria and heat waves on optimal building thermal mass control

This article investigates building thermal mass control of commercial buildings to reduce utility costs with a particular emphasis on the individual impacts of both adaptive comfort criteria and of heat waves. Recent changes in international standards on thermal comfort for indoor environments allow for adaptation to the weather development as manifested in comfort criteria prEN 15251.2005 and NPR-CR 1752.2005 relative to the non-adaptive comfort criterion ISO 7730.2003. Furthermore, since extreme weather patterns tend to occur more frequently, even in moderate climate zones, it is of interest how a building's passive thermal storage inventory responds to prolonged heat waves. The individual and compounded effects of adaptive comfort criteria and heat waves on the conventional and optimal operation of a prototypical office building are investigated for the particularly hot month of August 2003 in Freiburg, Germany. It is found that operating commercial buildings using adaptive comfort criteria strongly reduces total cooling loads and associated building systems energy consumption under conventional and building thermal mass control. In the case of conventional control, total operating cost reductions follow the cooling loads reductions closely. Conversely, the use of adaptive comfort criteria under optimal building thermal mass control leads to both lower and slightly higher absolute operating costs compared to the optimal costs for the non-adaptive ISO 7730. While heat waves strongly affect the peak cooling loads under both conventional and optimal building thermal mass control, total cooling loads, building energy consumption and costs are only weakly affected for both control modes. Passive cooling under cost-optimal control, while achieving significant total cost reductions of up to 13%, is associated with total energy penalties on the order of 1–3% relative to conventional nighttime setup control. Thus, building thermal mass control defends its cost saving potential under optimal control in the presence of adaptive comfort criteria and heat waves.     

既有采暖居住建筑节能改造实例分析

介绍了以北京市既有非节能住宅案例A、案例B节能改造对象,分析了其建筑围护结构热工性能、能耗指标、采暖系统的特点及不足。通过围护结构节能改造,建筑物能耗,可达到65％的节能目标。通过采暖系统分户计量改造,采暖系统可实现运行管理节能。